When optical transmitters and receivers are coupled by means of light-transmissive insulating materials, and when high electric fields prevail between transmitter and receiver, changes occur in the electrical characteristic values of the system components, in particular, in the values of the receiver. The influence of such electric field gives rise to partially irreversible effects generally in the receiver, for example, an increase in the reverse current, a reduction in the current amplification, and a change in the operating point. A considerable change in the electric characteristic values generally gives rise to a serious impairment of the effects of the associated semiconductor component.